Precision liquid delivery is an important function in the production and research of many products, especially for the medical and pharmaceutical industries. As in all equipment, ease of use and reliability, combined with accuracy, are extremely important in the successful performance of each application.
There are several main technologies which are commonly used in dispensing fluids. These include piston pumps, peristaltic pumps, time pressure systems, diaphragm pumps and gear pumps. Each of these technologies must incorporate some sort of valving technology along with a method for displacing fluid. It is generally understood that, in order to achieve accurate and reliable dispenses, positive displacement mechanisms have exhibited the best performance. Most positive displacement mechanisms incorporate out of phase check valves and a piston or other positive displacement mechanism to create suction and discharge.
Syringe pumps and rotary reciprocating pumps are most commonly used in the industry in order to accomplish small volume dispensing. The syringe pump utilizes check valves or other separate mechanical valving assemblies combined with a programmable stroke length adjustment. Due to the materials of construction and the fact that external valving is necessary, the pump is easy to use but often has long term reliability and priming problems.
Rotary reciprocating pumps, on the other hand, utilize the piston as an integral valving mechanism eliminating secondary valves, but incorporate a mechanical stroke length adjustment which is not for use by an operator. Additionally, both of these mechanisms typically incorporate one inlet and discharge connection as the maximum number of ports due to the design constraints of each mechanism.
It is therefore a primary object of the present invention to provide a rotary reciprocating positive displacement pump utilizing a rotary, reciprocating piston as an integral valving mechanism, which includes the benefit of multi-porting, and in which rotary shift of the piston and axial stroke length may be readily electronically adjusted, and in which the pump is self-priming, permits bubble clearing, and results in a fast and simple setup.
It is a further object of the invention to provide such rotary reciprocating pump, in which the dispensing resolution is reduced to nanoliter range, which is highly reliable in performance, and simple to use, and which may be instantaneously adjusted to dispense the same or other liquids at different dispensed volumes via the multi-porting feature .